import ../core
import ./framebuffer

proc CreateRenderPass*(
  device: VkDevice,
  format: VkFormat,
): VkRenderPass =

  var
    attachments = @[VkAttachmentDescription(
        format: format,
        samples: VK_SAMPLE_COUNT_1_BIT,
        loadOp: VK_ATTACHMENT_LOAD_OP_CLEAR,
        storeOp: VK_ATTACHMENT_STORE_OP_STORE,
        stencilLoadOp: VK_ATTACHMENT_LOAD_OP_DONT_CARE,
        stencilStoreOp: VK_ATTACHMENT_STORE_OP_DONT_CARE,
        initialLayout: VK_IMAGE_LAYOUT_UNDEFINED,
        finalLayout: VK_IMAGE_LAYOUT_PRESENT_SRC_KHR,
    )]
    # dependencies seems to be optional, TODO: benchmark difference
    dependencies = @[VkSubpassDependency(
      srcSubpass: VK_SUBPASS_EXTERNAL,
      dstSubpass: 0,
      srcStageMask: toBits [VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT],
      srcAccessMask: VkAccessFlags(0),
      dstStageMask: toBits [VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT],
      dstAccessMask: toBits [VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT],
    )]
    outputs = @[
      VkAttachmentReference(
        attachment: 0,
        layout: VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL,
      )
    ]

  var subpassesList = [
    VkSubpassDescription(
      flags: VkSubpassDescriptionFlags(0),
      pipelineBindPoint: VK_PIPELINE_BIND_POINT_GRAPHICS,
      inputAttachmentCount: 0,
      pInputAttachments: nil,
      colorAttachmentCount: uint32(outputs.len),
      pColorAttachments: outputs.ToCPointer,
      pResolveAttachments: nil,
      pDepthStencilAttachment: nil,
      preserveAttachmentCount: 0,
      pPreserveAttachments: nil,
    )
  ]

  var createInfo = VkRenderPassCreateInfo(
      sType: VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO,
      attachmentCount: uint32(attachments.len),
      pAttachments: attachments.ToCPointer,
      subpassCount: uint32(subpassesList.len),
      pSubpasses: subpassesList.ToCPointer,
      dependencyCount: uint32(dependencies.len),
      pDependencies: dependencies.ToCPointer,
    )
  checkVkResult device.vkCreateRenderPass(addr(createInfo), nil, addr(result))

proc BeginRenderCommands*(commandBuffer: VkCommandBuffer, renderpass: VkRenderPass, framebuffer: Framebuffer, oneTimeSubmit: bool, clearColor: Vec4f) =
  assert commandBuffer.Valid
  assert framebuffer.vk.Valid
  let
    w = framebuffer.dimension.x
    h = framebuffer.dimension.y

  var clearColors = [VkClearValue(color: VkClearColorValue(float32: clearColor))]
  var
    beginInfo = VkCommandBufferBeginInfo(
      sType: VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO,
      pInheritanceInfo: nil,
      flags: if oneTimeSubmit: VkCommandBufferUsageFlags(VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT) else: VkCommandBufferUsageFlags(0),
    )
    renderPassInfo = VkRenderPassBeginInfo(
      sType: VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO,
      renderPass: renderpass,
      framebuffer: framebuffer.vk,
      renderArea: VkRect2D(
        offset: VkOffset2D(x: 0, y: 0),
        extent: VkExtent2D(width: w, height: h),
      ),
      clearValueCount: uint32(clearColors.len),
      pClearValues: clearColors.ToCPointer(),
    )
    viewport = VkViewport(
      x: 0.0,
      y: 0.0,
      width: (float)w,
      height: (float)h,
      minDepth: 0.0,
      maxDepth: 1.0,
    )
    scissor = VkRect2D(
      offset: VkOffset2D(x: 0, y: 0),
      extent: VkExtent2D(width: w, height: h)
    )
  checkVkResult commandBuffer.vkResetCommandBuffer(VkCommandBufferResetFlags(0))
  checkVkResult commandBuffer.vkBeginCommandBuffer(addr(beginInfo))
  commandBuffer.vkCmdBeginRenderPass(addr(renderPassInfo), VK_SUBPASS_CONTENTS_INLINE)
  commandBuffer.vkCmdSetViewport(firstViewport = 0, viewportCount = 1, addr(viewport))
  commandBuffer.vkCmdSetScissor(firstScissor = 0, scissorCount = 1, addr(scissor))

proc EndRenderCommands*(commandBuffer: VkCommandBuffer) =
  commandBuffer.vkCmdEndRenderPass()
  checkVkResult commandBuffer.vkEndCommandBuffer()